How much iodine is too much?

NEW YORK: Iodine deficiency is a major health problem worldwide, but a new study points to the potential downsides of too much iodine.

Iodine is a mineral found in iodized salt, seafood, eggs, dairy and some breads. It is used by the thyroid gland to help regulate metabolism and development, especially in babies and children.

Iodine deficiency during fetal and early-childhood development is a leading cause of brain impairments in much of the world. So most research has been directed at the effects of inadequate iodine.

Less is known about how much iodine is too much. So for the new study, reported in the American Journal of Clinical Nutrition, Chinese researchers randomly assigned healthy adults to take various doses of iodine supplements for four weeks.

They found that at relatively higher doses -- 400 micrograms a day and up -- study participants began developing what's called subclinical hypothyroidism.

That refers to a dip in the body's thyroid hormone levels, but with no obvious symptoms of hypothyroidism -- which include problems like fatigue, depression, dry skin and weight gain.

In this study, people taking 400-microgram supplements were getting around 800 micrograms of iodine per day when diet was factored in.

So the findings suggest that people -- at least in China -- should get no more than 800 micrograms a day, according to the researchers, led by Wanqi Zhang of Tianjin Medical University.

That's different from what's recommended in the US, where National Institutes of Health guidelines say the safe upper limit for adults is 1,100 micrograms of iodine per day.

Still, the typical American would get much less than 800 micrograms of iodine a day through diet anyway, according to Dr. Elizabeth Pearce, an associate professor of medicine at Boston University who was not involved in the study.

That said, Pearce cautioned against taking iodine supplements with more than 150 micrograms in a daily dose. And most Americans could skip supplements altogether.

"Overall, we're iodine-sufficient," said Pearce, who studies iodine sufficiency and thyroid function.

But she said there are certain people who may need supplements, including pregnant women.

In the US, adults are advised to get 150 micrograms of iodine each day; pregnant women should get 220 micrograms, while breastfeeding moms are told to get 290 micrograms.

The American Thyroid Association recommends that pregnant and breastfeeding women take a vitamin with iodine because low iodine can increase the risk of miscarriage and thyroid problems in moms, in addition to mental disabilities in babies.

According to Pearce, vegans may also want to take a supplement. In a recent study, Pearce and her colleagues found that the average iodine level in a group of 63 vegans was lower than what's recommended -- though their thyroid hormone levels were in the normal range.

Vegans eschew all animal products, including dairy and eggs, so their iodine sources may be few.

WHO YOU ARE, WHERE YOU LIVE

The current findings are based on 256 healthy adults who had normal thyroid when they entered the study. Zhang's team, which did not respond to requests for comment, randomly assigned them to take one of 12 doses of supplemental iodine -- anywhere from 0 to 2,000 micrograms per day, for four weeks.

Of the people who took 400 micrograms, 5 percent developed subclinical hypothyroidism. And the numbers rose in tandem with the iodine dose: Of people on the highest dose (2,000 micrograms per day), 47 percent developed subclinical hypothyroidism.

"These are interesting data," Pearce said, "because we don't have a lot of information on iodine excess."

Subclinical hypothyroidism has no obvious symptoms, but studies have linked it to an increased risk of heart disease over the long term, Pearce noted.

Those studies don't prove that subclinical hypothyroidism is to blame. Still, they raise concerns that there could be health consequences.

But in general, Pearce said, it's thought that the effects of your iodine intake may depend on "who you are and where you live."

In certain parts of the world, the soil is low in iodine, and people who eat mainly local foods have a high risk of deficiency. In other parts of the world -- Japan, for example -- people have a high iodine intake starting early in life, and they seem to "tolerate" that high level, Pearce explained.

In China, natural iodine levels vary by region. The country introduced universal salt iodization in 1996, so the problem of iodine deficiency has been controlled in most areas.

But Pearce said it's not clear if the adults in this study had adequate iodine intake early in life. If not, that could be a factor in their response to iodine supplements. (Reuters) 

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Heart disease more likely in people with psoriasis: study

NEW YORK: People who suffer from psoriasis may want to pay extra attention to heart risks, since they may be at a greater risk for blocked arteries than those who don't have the skin disease -- although the risk increase is not that high, according to a U.S. study.

And the longer patients have psoriasis, the higher their risks are, said researchers, whose findings were published in the American Journal of Cardiology.

"One of the things that we've come to understand is that psoriasis is not a disease that's just limited to the skin," said April Armstrong of the University of California, Davis, who worked on the study.

Armstrong and her colleagues used records of patients who had undergone a heart scan called coronary angiography to compare the results of patients with and without psoriasis.

Psoriasis patients have patches of thick, red and scaly skin, which are thought to be caused by the immune system mistakenly attacking the body's own cells.

Among the nearly 9,500 patients included in the analysis, just over 200 were diagnosed with psoriasis. Compared to the other patients who underwent the heart screening, they were more likely to have a history of high cholesterol and to be heavier.

Overall, 84 percent of patients with psoriasis had narrowing of the arteries that supply blood to the heart -- a condition called coronary artery disease -- compared to 75 percent of patients without the skin condition.

The researchers also found that the longer patients had psoriasis, the greater this risks were.

"Our advice to patients with psoriasis is to make sure they get screened for their modifiable cardiovascular risk factors," said Joel Gelfand, a professor of dermatology at the University of Pennsylvania, Philadelphia.

These modifiable risk factors include smoking, blood pressure, cholesterol, glucose levels and body mass index (BMI), a measure of weight relative to height, added Gelfand, who was not involved with the study.

Armstrong said that while the study did not prove that the condition causes heart disease, the skin rash may be a sign that there is inflammation inside the body, too.

The findings fit with past studies that showed a connection between heart disease and inflammatory diseases such as rheumatoid arthritis, said Richard Krasuski, director of Adult Congenital Heart Disease Services at the Cleveland Clinic, who was not involved with the study.

"Certainly what they come up with makes biological sense," he added, although he cautioned that the rise in risk wasn't overwhelming and the findings were based on patients from only one medical center. (Reuters) 

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Healthy eating may help ADHD kids: US study

WASHINGTON: Simply eating healthier may improve the behavior of children with attention deficit hyperactivity disorder if therapy and medication fail, said a study published Monday in the journal Pediatrics.

Researchers, however, said that their review of recent controlled scientific studies had shown conflicting evidence on the impact of supplements and restricted diets - in some cases they were no better than the placebo effect.

Nutritional interventions should therefore be considered an alternative or secondary approach to treating ADHD, not a first-line attack, said the review by doctors at Northwestern University Medical School in Chicago.

"Supplemental diet therapy is simple, relatively inexpensive, and more acceptable to patient and parent," than strict additive-free diets that have been popular in the past, said the study.

"Public education regarding a healthy diet pattern and lifestyle to prevent or control ADHD may have greater long-term success."

The study reviewed research published on the sugar-restricted, additive-free Feingold Diet, megavitamin therapies, omega-3 fatty acid supplementation and the suspected link between ADHD and a "Western-style" high-fat, low-fiber diet.
source : GEO NEWS

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Alzheimer's: Diet 'can stop brain shrinking'

A diet rich in vitamins and fish may protect the brain from ageing while junk food has the opposite effect, research suggests.

Elderly people with high blood levels of vitamins and omega 3 fatty acids had less brain shrinkage and better mental performance, aNeurology study found.

Trans fats found in fast foods were linked to lower scores in tests and more shrinkage typical of Alzheimer's.

A UK medical charity has called for more work into diet and dementia risk.

The best current advice is to eat a balanced diet with plenty of fruit and vegetables, not smoke, take regular exercise and keep blood pressure and cholesterol in check, said Alzheimer's Research UK.

The research looked at nutrients in blood, rather than relying on questionnaires to assess a person's diet.

US experts analysed blood samples from 104 healthy people with an average age of 87 who had few known risk factors for Alzheimer's.

They found those who had more vitamin B, C, D and E in their blood performed better in tests of memory and thinking skills. People with high levels of omega 3 fatty acids - found mainly in fish - also had high scores. The poorest scores were found in people who had more trans fats in their blood.

Trans fats are common in processed foods, including cakes, biscuits and fried foods.

The researchers, from Oregon Health and Science University, Portland; Portland VA Medical Center; and Oregon State University, Corvallis, then carried out brain scans on 42 of the participants.

They found individuals with high levels of vitamins and omega 3 in their blood were more likely to have a large brain volume; while those with high levels of trans fat had a smaller total brain volume.

Study author Gene Bowman of Oregon Health and Science University said: "These results need to be confirmed, but obviously it is very exciting to think that people could potentially stop their brains from shrinking and keep them sharp by adjusting their diet."

'Strong potential'

Co-author Maret Traber of the Linus Pauling Institute at Oregon State University said: "The vitamins and nutrients you get from eating a wide range of fruits, vegetables and fish can be measured in blood biomarkers.

"I'm a firm believer these nutrients have strong potential to protect your brain and make it work better."

Commenting on the study, Dr Simon Ridley, head of research at Alzheimer's Research UK, said:

"One strength of this research is that it looked at nutrients in people's blood, rather than relying on answers to a questionnaire.

"It's important to note that this study looked at a small group of people with few risk factors for Alzheimer's disease, and did not investigate whether they went on to develop Alzheimer's at a later stage.

"There is a clear need for conclusive evidence about the effect of diet on our risk of Alzheimer's, which can only come from large-scale, long-term studies."

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Women's lung cancer risk not tied to childbirths

NEW YORK: A woman's lung cancer risk doesn't appear to be linked to the number of children she has, although some scientists had thought hormonal changes during pregnancy might protect against the disease.

That's according to a new report that sums up 16 previous studies on the topic, which researchers have explored to get a better understanding of lung cancer and possible treatments.

If lung cancer in women were tied to hormones the same way some breast cancers are, for instance, similar drugs might be effective against both diseases, said Jessica K. Paulus, who worked on the analysis.

So far, however, studies haven't agreed on whether or not pregnancies -- and by extension hormones -- play a role in lung cancer.

That was also clear from the new work, said Paulus, of Tufts University in Medford, Massachusetts.

"If you look at the component studies, they are all over the map," she told, adding that she and her colleagues had hoped to be able to explain that variation.

"We came up relatively empty-handed," Paulus said. "It makes it difficult to interpret our findings."

Lung cancer is the leading cause of cancer deaths in the US, according to the American Cancer Society.

The disease is rare in younger adults, but becomes more common as people grow old. Overall, the risk of getting lung cancer is about one in 13 for men and one in 16 for women. But these overall numbers include smokers, whose risk is many times higher than that of non-smokers.

"Both active smoking and exposure to second-hand smoking are some of the strongest risk factors for lung cancer," said Paulus. "Quitting smoking and quitting soon is associated with reducing your risk of lung cancer."

Despite the new findings, Paulus added that a link between childbirths and lung cancer still can't be ruled out. She said she hopes a more in-depth analysis of the existing evidence -- including detailed data on each woman -- might help close the issue.

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